In recent years, dispensing devices for a wide range of pasty and viscous substances such as toothpaste, food product such as cheese, creams and other materials have come into wide use. Especially popular are hand-held pumps which provide attractive, easy-to-use containers for use by consumers both at home and while travelling.
In particular, hand-held pumps for dentifrice materials such as toothpaste and gels (hereinafter referred to for convenience collectively as "pastes") have gained considerable consumer acceptance. They have become an alternative to tubes, but tubes are currently substantially less expensive than paste pumps now on the market.
Since pumps have properties many consumers prefer over tubes, it is believed that if a pump could be designed for manufacture at a cost equal to or less than tubes, sales of such a pump would increase substantially.
Pumps adapted for dispensing paste are generally found in International Classes G01F 11/00 and B67D 5/32 and in Class 222 in the U.S. Patent and Trademark Office. Representative thereof are the following U.S. Pat. Nos. issued in recent years: 4,511,068; 4,598,843; 4,437,591; and 4,657,161.
Although there are several types of pumps for pasty materials now on the market, there are none which are refillable. That is, when the pump contents are emptied, the entire pump must be discarded since there is no means by which the pump can be refilled. This is expensive, because the internal parts of the pump and the pump body are relatively expensive and if they could be saved through the use of a refill having a new supply of toothpaste or other pasty material, the consumer would benefit greatly, i.e., instead of having to pay for a new pump in addition to the product--which is what the consumer actually desires to purchase--the consumer could simply buy a relatively inexpensive refill containing the product and attach it to the pump, thereby saving the cost of purchasing a new pump mechanism.
One widely used type of hand-held pump utilizes an actuator mechanism which requires the application of pressure thereon by the user to draw up a notched rod which passes through the piston. The piston has connected to it a series of tangs, known as "dogs" which engage the notches as the piston is drawn up by the actuator so as to prevent the piston from thereafter moving downwardly. Another variation employs a smooth rod wherein the dogs press against the rod with sufficient force to prevent downward movement of the piston. PG,4 Dogs of this type thus make it impossible to remove the piston by withdrawing it down the rod. Consequently, since the piston must be removed in order to attach a refill with a new piston at its bottom--where the piston must be in draw-up type pumps, the existing inability to remove the original piston has prevented the development of a refill system for this type of pump. Since, as indicated, it would be highly desirable to provide a refillable pump, this technical problem is a primary problem which the art has not been able to overcome until the present invention.